Transient Heavy Element Absorption Systems in Novae: Episodic Mass Ejection from the Secondary Star
A high-resolution spectroscopic survey of post-outburst novae reveals
short-lived heavy element absorption systems in a majority of novae near
maximum light, having expansion velocities of 400-1000 km s<SUP>-1</SUP>
and velocity dispersions between 35 and 350 km s<SUP>-1</SUP>. A
majority of systems are accelerated outward, and they all progressively
weaken and disappear over timescales of weeks. A few of the systems
having narrow, deeper absorption reveal a rich spectrum of singly
ionized Sc, Ti, V, Cr, Fe, Sr, Y, Zr, and Ba lines. Analysis of the
richest such system, in LMC 2005, shows the excitation temperature to be
10<SUP>4</SUP> K and elements lighter than Fe to have abundance
enhancements over solar values by up to an order of magnitude. The gas
causing the absorption systems must be circumbinary and its origin is
most likely mass ejection from the secondary star. The absorbing gas
exists before the outburst and may represent episodic mass transfer
events from the secondary star that initiate the nova outburst(s). If
SNe Ia originate in single degenerate binaries, such absorption systems
could be detectable before maximum light.